1. Field of the Invention
The present invention relates to an automatic vending machine and, more specifically to a paper currency collection detection arrangement for an automatic vending machine, which automatically cuts off power supply when the amount of collected paper currency reached a predetermined high level.
2. Description of the Related Art
A variety of automatic vending machines have been disclosed for use to sell different consumer goods. Some automatic vending machines accept coins only. Some other automatic vending machines accept paper currency. An automatic vending machine accepting paper currency generally has means to detect the collection of paper currency and to cut off power supply when collected paper currency is full. According to conventional designs, counter means, photoelectric switch means, and micro-switch means are commonly used to detect the collection of paper currency. However, these conventional designs have drawbacks. The use of counter means greatly complicates the circuit design, and its maintenance work is also complicated. The use of photoelectric switch means greatly increases the installation cost. Further, the detection face of photoelectric switch means tends to be covered with dust, resulting in a false action. The use of micro-switch means is not durable. A contact error tends to occur after a long use of micro-switch means. There is also known still another design that uses a solenoid switch and a magnetic device to detect the collection of received paper currency. During operation of the automatic vending machine, the functioning of the solenoid switch tends to be interfered with external noises from surrounding metal members and electronic elements. Further, the magnetic force of the solenoid switch and the magnetic device may deteriorate after a long use, resulting in a low sensitivity.